EDIT: Figured it out - maybe someone will stumble on this thread searching for answers. I had to re-assign my physical CD-R drive to a lower letter than Daemon Tools. So now I mounted the game.cue for Quake under Daemon Tools to D: and my CD-R drive is set to Y: and music is working!

So I know there are tons of threads out there floating around on the internet about this, and I've successfully gotten the music to work with GLQuake on my Windows XP system by simply mounting the image included with the GOG release of Quake. I've done the exact same thing on my Windows 98 system and it's not working, I'm pretty much at a loss here. Things that I've tried:

1. Create a MUSIC folder in the Quake directory, trying both .OGG and .MP3 files (starting at Track02-Track09) in it
2. Same as above but putting the MUSIC folder under ID1 subdirectory
3. Extracting QUAKESPASM into my Quake directory, renaming Quakespasm.exe to GLquake.exe and launching it. This resulted in a complaint that the system doesn't have enough memory, or something about a .DLL error
4. Putting an audio CD into my CD drive, this works, Quake plays whatever disc I put into my drive, obviously REM doesn't really match the vibe of Quake so...
5. Mounting all 3 of the included disc images with DaemonTools, ensuring that the drive letters assigned are lower than my DVD/CDRW drive (which is D:)

It's kind of driving me up the wall at this point, and I may just buy an original copy off of eBay, but that bugs me too seeing how I already purchased it on GOG. What am I missing here? Like I said, mounting the image with Daemon Tools on my Windows XP system works just fine, I cannot figure out what is different about trying to do it on 98.

System specs:
Windows 98 SE + unofficial patch
PIII 800EB
384MB SDR Memory
GeForce 256 SDR
SB Audigy Gold

As a bonus, I also can't get the game to launch beyond 640x480 (adding -width 800 or 1024 and -bpp 32 or 16). I don't really mind playing it at 640x480 but it would be great to up the resolution in GLQuake if I could.